Cellular wireless technologies typically operate in a licensed frequency spectrum. A licensed frequency spectrum is a range of frequencies that are assigned to a particular entity (e.g., a particular wireless carrier) for use. As the available licensed frequency spectrums are limited and as demand rises for cellular wireless services, the amount of free spectrum available for use is limited.
In contrast to licensed frequency spectrums, there are various unlicensed frequency spectrums which allow for use of certain frequencies without an entity obtaining legal approval. These frequencies are shared amongst devices which wish to use them, and devices that use these spectrums have protocols to allow them to share the spectrum with other devices. Often these unlicensed spectrums are not licensed primarily for cellular wireless uses and often these spectrums are subject to contention or utilization by other devices.